Many types of folders or binders for the insertion of pages are well known. As far as is known these require a solid metal or plastic member along the spine of the folder to which the rings or other holding members are attached, and sometimes also contain some form of release mechanism in the form of levers, springs and the like. While these are satisfactory in many respects, sometimes the cooperating portions of the posts or rings become misplaced and thus do not completely meet so that a page or pages can become removed. Also the spring action of various binders such as three or four ring binders is very strong to such an extent that if the user is not careful injury can occur if the fingers are between the two portions of the ring closing on each other.
Also there are known paper binders having two flexible arms, the ends of which are pushed through a manila folder, and after the paper sheets are placed thereon the arms are bent parallel to the surface of the paper sheets, a metal washer desirably being placed over the arms before they are bent parallel to the paper. However these are only suitable for thin manila folders, and the arms often have the pointed ends upstanding to a degree so that injury to the users hands or fingers may occur.
U.S. Pat. No. 4,886,390 discloses a binder having a pair of rings loosely attached to a file or folder. The rings are split and provided with a hinge so that the rings can be opened at the split to receive perforations in the papers to be attached to it. A locking device is provided at the ends of the split to prevent circumferential rotation of the rings.
GB 2190331 shows a ring binder which includes a spine in the form of a rod and rings secured to the rod. Each ring is in two halves which are pivotally connected by a pivot pin at one end and are provided at the other end with hooks and recesses which are engageable with one another to secure the halves of the rings to each other.
ZA 8102974 is directed to a ring binder having fixed half-rings comprising pairs of prongs projecting from a base plate. The prongs of each pair are movable relative to each other from an open position to a closed position to define a continuous ring.